The present invention relates to silicon-polyester block copolymers which are made by effecting reaction between a polydiorganosiloxane having terminal aminoorganosiloxy units and a thermoplastic polyester in the molten state, while the resulting mixture is stirred under reduced pressure.
The present invention is based on the discovery that an aminoorgano terminated polydiorganosiloxane having the formula, ##STR1## can be contacted with molten, high molecular weight polyester, such as polyalkylene terephthalate or poly(methylmethacrylate) to produce a silicone-polyester block copolymer providing a wide range of thermoplastics, elastomers and thermosets, where R is selected from C.sub.(1-13) monovalent hydrocarbon radicals and substituted C.sub.(1-13) monovalent hydrocarbon radicals, R.sup.1 is selected from R radicals and C.sub.(1-8) alkoxy radicals, R.sup.2 is a C.sub.(2-13) divalent organo radical and n is an integer equal to from 5 to about 2000 inclusive. The silicone-polyester copolymers made in accordance with the invention can be used as thermoplastics, molding compounds, elastomers, impact modifiers, adhesion promoters, plastic additives, and adhesives.